Sudden Motion Sensor on rMBP

I just bought a 13' retina MacBook Pro and installed LiquidMac just for the heck of it. It works, apart from slight graphics glitches.
But that struck me as odd; LiquidMac works (as stated on the developer's website http://uri.cat/software/LiquidMac/) by reading the accelerometer that serves as SMS on hard disk equipped MacBooks.
The app hasn't been updated since long before the rMBP came along, so it definitely uses the SMS API; thus, if the rMBP was built from the start as a solid state computer (at least as far as storage is concerned), why should it have a sudden motion sensor? It's not used for anything else. Of course, some apps have come along that use it, and maybe Apple included it for compatibility's sake, but AFAIK the MacBook Airs don't have it, and including a hardware device that isn't used by the OS itself just to maintain backwards compatibility strikes me as very un-Apple.

(I am thoroughly puzzled by this.)

 

Still puzzled by this.

 

After a further bit of looking around, and confirmation that it doesn't turn off the fans — which I checked by chucking it in the air while playing four HD videos — there are two possibilities:

1- It's built into some other chip and it's so cheap that it doesn't matter
2- As read on reddit, it's a ploy by Apple so that people are tempted to do "drunk lightsaber **** with their laptops and smash them, necessitating a replacement. But that is merely a conspiracy theory."